1. Field of the Invention
The invention is in the field of display systems which use optics therein in a method for identifying image distortion from the display focal surface to an observer, and especially the use of projection photolithography to project the shadow of a high resolution rectilinear grid at the output of the display system off the optics and onto the object surface to etch a curved cross grid pattern on the object surface, in which the curved cross grid pattern is a direct image of the high resolution rectilinear grid pattern and identifies distortion inherent in the optics within the display system.
2. Description of Prior Art
Previous display systems have used off-axis paraboloids as reflectors, but they are useful only for small viewing angles. Circular toroidal reflectors have also been used as reflective surfaces. The circular toroid has been found to be better than the parabola but still has spherical aberration and astigmatism off the line of symmetry of the toroid. There has been no provision of layering curved cross grids on the focal surface of a display device to provide a rectilinear grid to an observer.